1. Technical Field
The disclosure relates to a focusing apparatus. More particularly, the disclosure relates to a method of focus that can detect and adjust a focus position, and a focusing apparatus and a detecting module thereof.
2. Description of Related Art
With booming development of the electronic industry, a market trend for a plenty of consumable electronic products (for example, mobile phones, cameras, projectors) is delicacy and miniaturization. To match such a trend of the electronic industry, machining methods for key parts of the consumable electronic products are essential. On the other hand, a plurality of micron process machining is also applied to fabrication processes of current solar cells or panels, for example, microcircuit repairing, micro-machining, cutting, welding, drilling, material modification, etc. Therefore, the former mechanical machining methods are gradually inapplicable due to limitation of a blade size and a mechanism thereof.
A current solution is to perform the machining through a high-precision and high speed laser, for example, laser drilling and laser cutting, etc. The precision of the laser machining can be influenced due to an uneven surface of a machining part, of which a focal point of the laser may depart from a machining surface during the processing, which may lead to a malfunction of the machining due to insufficient energy of the laser, or an error of a machining size due to an excessive light spot area. Therefore, an automatic focusing module has to be applied to achieve the precision machining.
FIG. 1 is a diagram illustrating an automatic focusing structure of a laser engraving machine disclosed by a U.S. Pat. No. 6,259,057B1. Referring to FIG. 1, the conventional laser engraving machine 100 applies a mechanical probe 101 to detect whether the laser is focused, and achieves an automatic focusing function by adjusting the laser beam according to a detection result. However the mechanical probe 101 has to directly contact the surface of the machining part for detecting, and such detecting method generally causes a damage or contamination of the surface of the machining part, and limited by the mechanical structure, a precision thereof cannot be effectively improved, so that the machining apparatus applying such detecting method is not accord to a standard of a current micro-machining process.
FIG. 2 is a structural diagram illustrating a microscope disclosed by a U.S. Pat. No. 7,298,549B2. Referring to FIG. 2, to improve the machining precision, a current machining machinery generally applies an optical automatic focusing method to substitute the mechanical focusing method, and a common automatic focusing type is a confocal optical focusing. Generally, the confocal optical focusing requires relatively more optical devices (for example, a spectroscope 201, a filter 202, a focus lens 203 and optical lenses 204, 205, etc.) to guide the light to a detector 210, so as to detect whether the light is focused. Moreover, according to such automatic focusing method, a defocus direction cannot be directly identified, and the focusing lens 203 has to be shifted for a distance to identify whether the machining part is in a front focus state or a back focus state. Therefore, such focusing method may lead to problems of high cost and a great size.